All-relay selective calling system



July 28, 1953 R HERRlCK 2,647,250

ALL-RELAY SELECTIVE CALLING SYSTEM Original Filed Nov. 25, 1949 INVENTOR. 8 ROSWELL H. HERRICK ATTY.

Patented July 28, 1953 I 2,647,250 ALL-RELAY SELECTIVE CALLING SYSTEM Roswell H. Herrick, Lorain, Ohio, assignor to Automatic Electric Laboratories, Inc., Chicago, 111., a corporation of Delaware Original application November 25, 1949, Serial No. 129,488, now Patent No. 2,600,648, dated June 17, 1952.

Divided and this application November 30,1951, Serial No. 259,117

1, This invention relates to an all-relayselective calling'system of the type wherein one outof a large number of receivers incommunicati-cn with a single transmitter may be alerted for conversation. 1

It is an object of this'invention to provide an all-relay selective calling system in which a particular series of digital pulses is individual to the operation ofeach receiving station. 1

The registering circuit used in conjunction with the invention wherein two registering relays and a temperature-sensitive resistor provide a response to a three digit system is disclosed in the application of Roswell H. Herrick, Serial No. 129,488, now Patent No. 2,600,648, issued June 17. 1952, of which this application is a division.

I Another object of the invention is to provide a selective calling system including a series of counting relays arranged to be energized sequentially in which a series of condensers is arranged to speed the release of each counting relay when its locking circuit is broken. I

Other objects of the invention will be apparent from the following specification taken in connection with the accompanying drawing;

Referring generally tothe drawing a receiver 6 picks up pulse signals from a transmitter (not shown). These pulses areutilized to energize a pulse relay I0. Operation of the relay I6 energizes a SlOWr-ICIEQSB relay 20 and also a series of five counting relays 30, 40, 50, 60 and Min sequence. The operation of each counting relay breaks a locking circuit for the preceding counting relay so that only one counting relay will beoperated at a time. Each counting relay has contactswhich control one of a series of terminals I to 5. The terminals Ito are accessible for at-. tachment of three registering relay leads I II, I I2 and I I3. These leads are connected to terminals I to 5 in accordance with the call number assigned to .the particular unit inquestion, lead III being connectedto the terminalrepresenting the first digit, lead I I2 the second digit, and lead I I3 the third digit. H

The release of slow-release relay 20 at the conclusion of the pulse .orpulses constituting a particular digit actuates a relay 80 which closes its contacts 82 to complete a condenser discharge circuit through one of the terminal I to 5 and lead III provided lead III is connected to a terminal which has contacts closed in response to the called digit. If the discharge path is the proper oneth-e condenser discharge energizes a registering relay 90, which looks up and prepares,

6 Claims. (01. 340--168) I00 which is operated in response to a particular second digit pulse series. I

Relay I00, upon being energized, has contacts which complete a locking circuit for itself and a break the locking circuit of relay 90. If a third series of digit pulses then complete Ia circuit through lead I I3 relay 90 is reoperated. It is thejoint operation of relays 99 and I09 which completes a circuit to an alarm signal I09. A more detailed explanation of the operation of. the various circuits in the unit illustrated will be given hereinafter.

While only a single unit is showncn the drawe ing a receiving system is composed .of a number of such units wherein thereceivers are in communication with the same transmitter. All of the units are identical in construction, the only difference being that leads I I I, I I2 and I I3 are connected to different numbers and sequences of terminals I to 5 in order that only one unit may be signaled by a particular series of digital pulses.

The receiver 6 may be of the conventional type;

of radio receiver. A pair of leads I and 8 communicate digit pulses picked up by receiver 6 to the relay II]. The first pulse on relay I0 closes contacts I3 to complete the following circuit for, the operation of relay ground, contacts 8| contacts I3, relay 20, and battery to ground. Relay 26 then remains operated due to its slow to release characteristics for the series of impulses making up a single digit but releases during the pause between digits.

Reception of the carrier on receiver 6 completes a circuit for the operation of a squelch relay I30.

Relay I30 closes its contacts I3I to furnish locking ground for the subsequent operation of relays and IOU in a manner to be explained hereinafter.

Before receipt of a pulse a condenser I4 was charged through contacts I2 by the following circuit: ground, condenser I4, contacts I 2, resistor Indirect current source I5, and ground. Resistor I8 is present in the circuit for protective purposes and may conveniently have a resistance of about 1,000 ohms. The direct current source IB-may conveniently have a potential of about volts.

On each pulse of relay It the contacts I2 are opened and the contacts I I closed to create a con-.

tacts I I, contacts 63, contacts 53, contacts 43,. contacts 33, relay 30, and battery to ground.

Upon receipt of the pulse from condenser I 4, relay 30 looks up through its contacts 3] by the following circuit: ground, battery, relay 30, contacts 3|, contacts 41, contacts 51, contacts 61, contacts 71, contacts 3|, and ground.

Upon operation, relay 30 opens its contacts 33 and closes its contacts 32 to prepare a circuit for the operation of relay 40. Relay 30 also closes its contacts 34 to prepare a circuit for the operation of relay 80 which will be completed upon the release of relay 20. Contacts 35 of relay 30 are closed to prepare a condenser discharge circuit through terminal I. If no further pulses are received relay 30 remains operated until its locking circuit is interrupted by operation of relay 80. In this event the digit 1 would be recorded on relay 90 at stations which had call numbers beginning with the digit 1.

A second pulse following before the release of relay 20 passes through contacts 32 to operate relay 40. This relay then closes its X contacts 4| to complete a locking circuit for itself through contacts 57, 67, 11, BI and ground. Relay 40 then opens its contacts 'l-I to break the locking circuit of relay 30 and closes its contacts 46 to enable the discharge of a condenser 48 to speed the release of relay 30.

Condensers 48, 53, 68 and 3'8 all serve the purpose of speeding the release of one of the counting relays. The operation will be explained with reference to condenser 48. This condenser is initially charged through the following circuit: ground, direct current source I5, resistor I'I, condenser 48, contacts 41, 51, 61, TI and BI and ground. Resistor I1 is placed in the circuit for protective purposes and many conveniently be of about 10,000 ohms resistance.

When contacts 41 are opened the charging path for condenser 48 is broken and when contacts 45 are closed the condenser plate with the positive charge is grounded and the plate with the negative charge is connected through relay 30 in opposition to the battery current which has a positive ground. The relay battery potential is about 48 volts while the condenser 48 potential is about 150 volts. This high condenser potential in opposition to the battery current quickly releases relay 30.

When relay 40 is operated its contacts 43 are opened and its contacts 42 closed to prepare a circuit for the operation of relay 50. Its contacts 44 and 45 are closed to prepare circuits for the operation of relay 80 and through terminal 2 respectively. Thus if there are only two pulses relay 40 alone of the counting relays will be energized and a circuit through terminal 2 will be prepared in all stations and completed through relay 40 in stations which have the digit 2 as the first digit in their call numbers.

If a third pulse is delivered through relay I before relay 20 releases, relay will be energized by the discharge of condenser I4 through contacts 42 and its various contacts will be operated in a manner exactly analogous to that outlined above for relay 40. Similarly a fourth pulse will energize relay 68 through relay 50 contacts 52 and a fifth pulse will energize relay I0 through relay 58 contacts 62. The embodiment illustrated shows five counting relays which allows for a calling system utilizing digits 1 to '5. More counting relays may be added if an expanded digit system is desired.

The registering circuit consists of relays 90 and I00 with their accessory circuits. The first incoming signal passes through lead III, the second through lead I I 2 and the third through lead I I3. These leads are connected to terminals I to 5 in accordance with the number assigned to the unit. For example, for number 531 lead III would be connected to terminalS, lead II2 to terminal 3, and lead II3 to terminal I. For number 222, all three leads would be connected to terminal 2.

The registering relays 90 and I00 are initially energized by a condenser discharge circuit responsive to operation of relay 80. When relay is released a registering relay condenser 84 is charged from direct current source I5 through protective registor I6 and contacts 83.

With conclusion of a pulse or pulses constituting a single digit an operating circuit is prepared for relay 80 through one of contacts 34, 44, 54, B4 or I4. Upon the conclusion of the series of pulses relay 20 releases to complete the circuit for relay 80 through contacts 2I.

At its contacts 8I relay 80 breaks the locking circuit for whichever counting relay is operated. At its contacts 83 relay 80 opens the charging circuit of condenser 84 and at its contacts 82 closes a discharge circuit for condenser 84 through whichever of terminals I to 5 has its associated counting relay operated.

If, for example, the number of the unit is 534 and this is the unit being called the first series of pulses will leave counting relay T0 operated and contacts I5 will be closed. Relay will then be energized through the following circuit: ground, condenser 84, contacts 82, contacts I5, terminal 5, lead III, contacts I05, contacts 92, relay 90, and battery to ground.

Relay 90 looks up over its X contacts 9| by the following circuit: ground, battery, relay 90, contacts 9|, contacts I03, contacts I3I and ground.

At its contacts 03 relay 90 prepares a circuit for the operation of relay I00 by a condenser discharge through conductor II2.

Conductor H2 is connected to terminal 3. When relay 20 releases at the conclusion of the pulses representing digit 3, relay 80 operates and condenser 84 discharges through contacts 82 and 55, terminal 3, conductor Il2, contacts 93, contacts I04, relay I00, and battery to ground.

Relay I00 then locks up over its X" contacts I III through contacts I3I to ground. At the same time the contacts I03 are opened to break the direct locking circuit of relay 00 and the contacts I02 are closed to complete the following circuit for a temperature-sensitive resistor I08; ground, contacts I3I, resistor I08, contacts I02, contacts 95., resistor 96, and battery to ground. Resistor 98, which is in the circuit for protective purposes, may conveniently have a resistance of about 1,000 ohms.

The temperature-sensitive resistor I00 is of the type which ofifers high resistance when it is cold but very little resistance when it is heated. Consequently, although it is momentarily in the locking ground circuit of relay 90 when its circuit is first prepared it ofiers such high resistance on account of its cold state that the locking circuit of relay 90 breaks at the X contacts SI. The contacts 05 then close and resistor I 08 heats up to a point where it offers little resistance to the flow of current.

When the third digit (i in the assumed example) is counted on relay 60 relay I00 contacts I06 are closed and the following circuit is thereby provided for the reoperation of registering relay 80': ground, condenser 84, contacts 82 and 05,

terminal '4, conductor II3, contacts I06 and 92, relay 90, and battery to ground.

Relay 90 is now locked up over the following circuit through resistor I08 which is hot and therefore offers little resistance: ground, battery, relay 90, contacts 9I, contacts I02, resistor I08, contacts I3 I, and ground.

Relays 90 and I00 are now both operated and their contacts 94 and I0! are closed to complete a circuit for the operation of alerting signal I09.

The three-digit five-numbered system illustr-ated will allow for 125 calling stations. If there are this many stations the first digit will operate relay 90 in 25 of the stations, the second will operate relay I00 in five of the 25, and the third will reoperate relay 90 in one of the five to give an alerting signal only at the station called. The stations which had relay 90 or I00 operated but did not complete the call will remain partially operated until the carrier ceases at which time relay I30 will release and open its contacts I3I. This will break the locking circuits for Whichever of relays 90 and I00 are operated. The operation of relay 80 had previously opened its contacts 8| to release any of the counting relays which may have been locked.

While the preceding description has reference to a single embodiment of the invention this should not be construed to limit the scope of the invention other than as necessitated by the appended claims.

What is claimed is:

1. In a counting relay circuit, a plurality of counting relays operable in sequence by digital pulses, a locking circuit for each of said relays, all except the last of said locking circuits passing through contacts of the succeeding relay which open when said succeeding relay is energized, a condenser associated with each locking circuit, means for charging said condensers, and contacts on each relay except the first for discharging said condenser through the locking circuit of the preceding relay, the condenser discharge being opposed to the battery current holding the said preceding relay in the operated condition whereby the said preceding relay is very quickly deenergized.

2. A quick-release circuit for a relay comprising a relay having a winding, a holding circuit for said relay including said winding, means for closing said holding circuit to thereby establish a current flow therein in one direction, a condenser, means for charging said condenser, and means for including said condenser in said holding circuit with the winding of said relay, said condenser discharge establishing a current flow in said circuit in a direction opposed to that of the original holding current in the circuit to thereby accelerate the release of said relay.

3. In a selective signalling unit, means for receiving a plurality of pulses, a pulse relay, means for operating said pulse relay responsive to said pulses, a plurality of counting relays, means operated responsive to the operation of said pulse relay for sequentially operating said counting relays, each counting relay having a locking circuit, each locking circuit except the last including contacts of the next succeeding counting relay, said contacts opened by the operation of the next succeeding counting relay, a plurality of condensers, a charging circuit for said condensers, each condenser having a discharge circuit, each discharge circuit except the last ineluding contacts of the next succeeding counting relay, said last contacts closed by the operation of the next succeeding counting relay, each of said discharge circuits including the winding of one of said counting relays preceding the counting relay having the said closing contacts of said discharge circuit, whereby the operation of said relay which break the locking circiut to the preceding relay completes the discharge circuit to speed the release of the preceding relay to cause a rapid sequential operation of said counting relays.

4. In a selective signalling unit, means for receiving a plurality of groups of pulses, a pulse relay, means for operating said pulse relay responsive to said pulses, a slow release relay, an operating circuit for said slow release relay controlled by said pulsing relay, whereby said slow release relay restores between groups of pulses, a plurality of counting relays, means operated responsive to the operation of said pulse relay for sequentially operating said counting relays, means operated responsive to the particular counting relay operated at the end of each group of pulses and the restoration of said slow release relay at the end of each group of pulses for indicating the operated counting relay, each counting relay having a locking circuit, each locking circuit except the last including contacts of the next succeeding counting relay, said contacts broken by the operation of the next succeeding counting relay, a plurality of condensers, a charging circuit for said condensers, each condenser having a dischange circuit, each discharge circuit except the last including contacts of the next succeeding counting relay, said contacts closed by the operation of the next succeeding counting relay, each of said discharge circuits including the winding of one of said counting relays preceding the counting relay having the contacts included in said discharge circuit, whereby the operation of said relay which breaks the locking circuit to the preceding relay completes the discharge circuit to speed the release of the preceding relay to cause a rapid sequential operation of said counting relays.

5. In a selective signalling unit as claimed in claim 4, said fourth means comprising a series of terminals, one of said terminals for each of said counting relays, circuits connected to each terminal, a condenser, said condenser discharged through the circuit of the terminal corresponding to the counting relay operated at the end of each group of pulses.

6. A quick-release circuit for a relay comprising a first relay having a winding, a holding circuit for said first relay including said winding, means for closing said circuit to thereby establish a current flow therein in one direction, a condenser, means for charging said condenser, a second relay, means operated by said second relay to sequentially break said holding circuit and remake said holding circuit by interposing said condenser in said holding circuit, said condenser discharging through said winding of said first relay in said circuit, said condenser discharge establishing a current flow in said circuit in a direction opposed to that of the original holding current in the circuit to thereby accelerate the release of said relay.

ROSWELL H. HERRICK.

No references cited. 

